Telephone system



Fla, 3

T0 LINE FINDER BAN/(S 7'0 CONNECTOR BANKS TO LINE E. VROOM TELEPHONE SYSTEM Filed Sept. 28, 1940 BAN/(S }TO LINE FINDER FIG. 2

7'0 LINE FINDER BANKS T0 CONNECTOR "3/ iA/l/ENTOR E. VROOM B) 6?.6? CwdL ATTORNEY 7'0 LINE 7'0 LINE T0 CONNECTOR l -fi BANKS Aug. 5, 1941.

Patented Aug. 5, 1941 syn TELEEHUNE Edward Vrooni, fissining, N. Y assignor to Bell Telephone Laboratories, incorporated, York, N. Y a corporation of New York New 10 Claims.

lhis invention relates to telephone systems and particularly to measured service systems.

It is the object of the invention to enable the operation of a calling subscribers message register when the call is answered and thereafter the periodical reoperation of the register during the time the talking connection is maintained between the calling and called subscribers stations.

The invention is an arrangement in a telephone system for operating a calling subscribers message register by the application of a booster battery potential to the line conductor to which the line cut-off relay is connected. According to one feature of the invention message register is connected to this line conductor through a gas-filled tube, the energization of the tube being controlled by a lamp or other ene ,y radiating element. The lamp may be conn ted either in parallel or in series with the line cuwoii relay. The application of booster battery potential to said conductor is effective to hold the line cut-off relay and energize the the radiation from the lamp being effective, in combination with the application of booster battery potential, to ionize the gas in the tube; vhereupon the message register operated in series with the tube.

According to another feature the message reg conductor to which the line cut-off relay corn ,9

nected by the energization of a adjacent the gas-filled tube, the radiation of energy from the lamp being effective to icnize the gas in the tube and thus close the register operating cir wit. The lamp may be connected either in parallel or in series with the line cut-oii reiay. The meter operating circuit includes a trap former winding through which an alternating potential of a low frequency, such as 643 cycles is impressed across the tube to effect its perrnan deenergization upon disconnection of the booster battery potential from the line conductor.

The invention will be further explained by de scribing the system and circuit arrangements in which the features of the invention are enibodied, such a system being shown schematically in the drawing which forms a part of this invention. The invention is not limited in its application to the particular system or arrangements shown in the draw lg but is generally applicable to measured service communication systems.

Referring to the drawing:

Fig. 1 represents a telephone system which comprises subscribers stations A and B, lines Li and LX, line circuit LCI, line finder LF, selector Si, a message rate trunk circuit MET connecting the line finder LE to the selector'si. and connectors Cl and C2.

Each of Figs. 2, 3 and 4 shows a modification of the line circuit LCl of Fig. l.

The subscribers stations are of the common battery type which include a dial or impulse sender for controlling the operation of selector and connector switches through which connections with called subscribers are established. Two batteries are shown, the one WilJhOllt designation being the usual central office battery. The other battery is used as a booster battery and is marked BB.

The line finder switch LF, selector switch Si and connector switches Cl and C2 are of the well known two-motion step-by-step type. Reference may be had to pages 53 to 65 inclusive of Automatic Telephony, 2nd edition by Smith and Campbell for a description of the structure of said switches and their operation whenused as selectors and connectors. Reference may be had to the patent to R. L. Stekely, No. 1,799,654 of April '7, 1931,,for a description of the operation of a two-motion step-byetep line finder.

The line circuit LCl shown in Fig. 1 con-- prises a line relay 353, a line cut-oif relay 35, a message register MR connected through a gasfilled tube GT to conductor 33 in parallel with the line cut-oil relay 3'5 and in parallel with a lamp adjacent the gas-filled tube GT. The operation of, the line relay 39 upon initiation of a call at station A is effective, as described in the aforementioned patent to R. L. Stokely, to start an idle line finder LF, the cut-01f relay 35 being operated, by the application of ground potential to conductor fi l, as soon as the calling line is connected by a line finder LP to the associated message rate trunk circuit MET andfirst selector Si. Relay 35 locks to conductor fi l and connects conductor 3% to the lamp 36 and anode element of tube GT. The current through the lamp 33 is limited by a resistor ill to prevent the lighting of the lamp upon connection of ground potential to conductor 3%.

' The message rate trunk circuit MRT comprises a supervisory relay 5?] which is operated by a reversal of the current, when the called subscriber answers, to start a timing mechanism TA which measures off unit intervals of time during which the talking connection between the calling and called stations is maintained.

The selector SI associated with the line finder LP is operatively controlled by the impulses created by the dialing of the first digit of a called subscribers number to select a corresponding group of terminals and an unguarded set of terminals therein "leading to a succeeding switch through which the desired connection may be established. Succeeding digits dialed by the calling subscriber affect the operation of intermediate selectors, if any, and a connector C2 to complete the connection with the called line. The connection is maintained under thecontrol of the calling station by the connection of ground potential in the connector C2 to the test terminal in the bank of selector SE. The selector SI, line finder LF and cut-01f relay 35 are all held operated by this ground potential in usual manner. The connector C2 is arranged to ring the called station; and, when the callis answered, the connector reverses the current through the windingsof-the supervisory relay-5? toeffect itsoperation. Relay-50 closes a circuit for operating the start magnet .5! of timing mechanism .TA, which mechanism may be individual to the trunk .circuitMRT or common to a plurality of such trunk circuits. .Assoon asthe timing mechanism moves .out of normal position to start-the timingeofan .interval for which one operation of the callingsubscribers message register is required, .contact..52 closesa circuitfor .operatingrelay 46. Relay lfi disconnects the-holdingground potential from conduct0r 49 and closes-a circuit from boosterbattery EBB, through the front contact of relay 4%, conductor #9,.lower brush of .line finder LF,.conductor 34, frontcontact of relaytfi conductor 33, and through lamp 38 in parallelwith the cutoff relay-35. 'The lamp 36 is thereby lighted, the radiation of energy from-the lampthrough the gas intube GT and application of booster battery potentialbeing eiiective to break down tube GT and operate'the message register MR. When relay 45 releases, the holding. groundwpotential is again applied --to conductor 49 .in place of booster battery potential, thereby deenergizing theclamp '36, tube GT- andregistenMR. .Each

succeeding closure :of timing contact fiz, while the talking-circuit is maintained, effects the reoperationof relayefi :and register MR.

The line circuit shown in Fig.2 is similar to that shown in Fig. -1 except that the lampal fi is connected in --series withthe winding of the line 'cut-offrelay- 35 instead :of in parallel with battery iBB. Upon application of booster battery potential'to conductor 34 in place of ground :potential, the lamp '36 isenergized'to cause ionization of t-hegas in, and breakdown 'of, tube GT; whereupon -a=circuit isclosed from booster battery through the left winding of transformer 38, resistor 3l,ra-nd the "Winding of the" register MR to operate the register. Thetube GT is extinguished'byearlh opposing half cycle of alternating ,potential applied by source 39 through transformer 38; butaslong as lamp36 is lighted,

thetube .GT'is again-energized during the other half cycle. Each of the message registers is designed to be slow in releasing so that it will not release upon deenergization of tube GT during the opposing half cycle of alternating potential from source 39. If necessary, a condenser can be connected in parallel with each of the registers to prevent release of the register until after lamp 36 is extinguished. When ground potential is again applied to conductor 49, in place of booster battery potential, the cut-oil relay 35 is held operated but the lamp 36 is partially deenergized. Upon deenergization of lamp --36, the tube GT is deenergized and register MR released by the impression of an opposing half cycle of a low alternating potential, such as 60 cycles, through transformer 38 in series with the booster battery BB.

Although the arrangements above described contemplate a single operation of a calling subscribers message register for each conversation unit, the arrangement may be one in which the register is operated once or a plurality .of times when a call is answered .or for each unit of conversation,.the number of operations depending on the zone within which the called station is located with respect to the calling station.

What is claimed is:

1. In a telephone system, a line circuit comprising a control conductor, a line cut-oil relay, a gas-filled tube, a lamp adapted to radiate energy to ionize the gas in said tube, means connecting said relay and said lamp in parallel to said conductor, and a message register, said'register connected in series with the tube for operation upon breakdown of the tube, means for applying ground potential to said conductor to operate said relay, said lamp being insufliciently energized upon application of ground potential to said conductor to effect breakdown of the tube, and means for applying booster batterypotcntial in place of ground potential to said conductor to hold said relay and to fully energize said lamp to effect breakdown of the tube.

2. In a telephone system, a line circuit comprising a line cut-off relay, a control'conductor, a gas-filled tube, a lamp adjacent said tube, means connecting said relay, said lamp and the anode of said tube to said conductor, and a mes sage register connected to the cathode of said tube for operation upon breakdown of said tube, said relay being operatively energized by the application of ground or booster battery potential to said conductor, said lamp being insufficiently energized by the application of ground potential and sufficiently energized by the application of booster battery potential to said conductor to radiate light through the gas in said tube to reduce the potential difference required across its elements to effect breakdown, thereby to effect breakdown of the tube and operation of the register responsive to application of booster battery potential to said conductor.

3. In a telephone system, a line circuit comprising a line cut-off relay, a control conductor, a gas-filled tube, a lamp adjacent said tube, means connecting said relay, said lamp and the anode of said tube in parallel to said conductor, and a message register connected to the cathode of said tube for operation upon breakdown of said tube, said relay being operatively energized by the application of ground or booster battery potential to said conductor, said lamp being insufficientl y energized by the application of ground potential and sufficiently energized by the application of booster battery potential to said conductor to radiate light through the gas in said tube to reduce the potential difference required across its elements to effect breakdown, thereby to effect breakdown of the tube and operation of the register responsive to application of booster battery potential to said conductor.

4. In a telephone system, a line circuit comprising a line cut-off relay, a control conductor, a gas-filled tube, a lamp adjacent said tube, means connecting said relay and said lamp in series to said conductor, the anode of said tube being connected to said conductor, and a message register connected to the cathode of said tube for operation upon breakdown of said tube, said relay being operatively energized by the application of ground or booster battery potential to said conductor, said lamp being insufficiently energized by the application of ground potential and sufficiently energized by the application of booster battery potential to said conductor to radiate light through the gas in said tube to reduce the potential difference required across its elements to effect breakdown, thereby to effect breakdown of the tube and operation of the register responsive to application of booster battery potential to said conductor.

5. In a telephone system, a line circuit comprising a line cut-ofi relay, a control conductor, a gas-filled tube, a lamp adjacent said tube, means connecting said lamp and relay to said conductor, said relay being operatively energized responsive to the application of ground or booster battery potential to said conductor, said lamp being insufficiently energized by the application of ground potential and sufficiently energized by the application of booster battery potential to said conductor to radiate light through the gas in said tube, a message register and battery connected in series with the elements of said tube, breakdown of the tube and operation of the register being effected by the lighting of said lamp.

6. In a telephone system, a line circuit comprising a line cut-off relay, a control conductor, a gas-filled tube, a lamp adjacent said tube, means connecting said lamp and relay in parallel to said conductor, said relay being operatively energized responsive to the application of ground or booster battery potential to said conductor, said lamp being insufficiently energized by the application of ground potential and sufiiciently by the application of booster battery potential to said conductor to radiate light through the gas in said tube, a message register and battery connected in series with the elements of said tube, breakdown of the tube and operation of the register being effected by the lighting of said lamp.

7. In a telephone system, a line circuit comprising a line cut-01f relay, a control conductor, a gas-filled tube, a lamp adjacent said tube, means connecting said lamp and relay in series with said conductor, said relay being operatively energized responsive to the application of ground or booster battery potential to said conductor, said lamp being insufficiently energized by the application of ground potential and sufficiently energized by the application of booster battery potential to said conductor to radiate light through the gas in said tube, a message register and battery connected in series with the elements of said tube, breakdown of the tube and operation of the register being effected by the lighting of said lamp.

8. In a telephone system, a calling subscribers station, line and line circuit, said line circuit comprising a line cut-off relay, a control conductor, a gas-filled tube, a lamp adjacent said tube, means connecting said relay, lamp and the anode of said tube to said conductor, and a message register connected to the cathode of said tube for operation upon breakdown of the tube, a called line and station, means including a message rate trunk circuit connecting said calling and called stations for conversation, means applying ground potential to said conductor to operate said relay, the current through said" lamp due to the application of ground potential to said conductor being ineffective to light said lamp, means associated with said trunk circuit for measuring oiT intervals of time while said connection is maintained, each such interval constituting a message unit for which one operation of the calling subscribers register is required, means effective at the beginning of an interval for applying booster battery potential to said conductor in place of ground potential thereby to hold said relay and light said lamp, the energy thereupon radiated by said lamp being effective to ionize the gas in said tube and thus effect the operation of said register.

9. In a telephone system, a line circuit comprising a line cut-off relay, a control conductor, a gas-filled tube, a lamp adjacent said tube, means connecting said relay and lamp in parallel to said conductor, and a message register, a source of potential connected in series with said register and said tube, said tube being normally deenergized, means for applying ground potential to said conductor to operate said relay without lighting said lamp, means for applying a potential to said conductor to hold said relay and light said lamp, the energy radiated by said lamp being effective to break down the tube and operate said register, and means comprising a transformer for superimposing an alternating potential on said breakdown potential to extinguish the tube when said lamp is extinguished.

10. In a telephone system, a line circuit comprising a line cut-off relay, a control conductor, a gas-filled tube, a lampadjacent said tube, means connecting said relay and lamp in series with said conductor, and a message register, a source of potential connected in series with said register and said tube, said tube being normally deenergized, means for applying ground potential to said conductor to operate said relay Without lighting said lamp, means for applying a potential to said conductor to hold said relay and light said lamp, the energy radiated by said lamp being effective to break down the tube and operate said register, and means comprising a transformer for superimposing an alternating potential on said breakdown potential to extinguish the tube when said lamp is extinguished.

EDWARD VROOM. 

